On Thu, 9 Dec 2004, Digby Millikan wrote: > Meng-Ying, > > Even if your population variance and sill do not match identically, > the sample sill should still be a better estimate than the sample variance, > when you consider the amount of clustering which occurs in sampling. > > Digby >
All right, if you think the clustering of data values (I'm not talking about clustering of locations) are not be part of the representation of population. I just found an example that I can use as population, with 2500 points and it's 2-D (in the GSLIB manual, second realization of SGSIM.OUT-- if you happen to have this data set) and found the sill and variance of this population not matching (sill~20, variance=18.63). I intended to use a smaller sample so everyone can have fun playing the data (even if you use M$-Excel to calculate the variogram), which also speaks out more what I'd like to say. But seems like people are more interested in discussing the size of population. . . I'll leave it here then, if nobody found any problem estimating population variance using the sill value. Maybe I'm just psychologically not comfortable estimating variance like that. . . (I'll probably follow you people if I found no theoretic derivation for my thinking.) It's fun discussing with you people though, and I'm happy to have this much discussion for my debut. Meng-ying
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